Objective:To summarize clinical characteristics of Kawasaki disease (KD) in infants younger than 6 months and explore indices for early diagnosis. Methods: Retrospective data from 43 cases of KD in infants younger than 6 months were collected in Nanjing Children’s Hospital from March 2005 to February 2009, and compared with 238 cases of KD in children older than 6 months in the same period. Results: Among 43 cases of KD in infants younger than 6 months, male-female ratio was 2.31∶1. Compared with 238 cases of KD in children older than 6 months, the incidence of some clinical features, such as BCG vaccination erythema, symptoms in digestive system and nervous system at acute period were increased significantly(P < 0.05), while cervical lymphadenopathy was absent in 43 cases of KD in infants younger than 6 months. The levels of neutrophils(N%), platelet(PLT), erythrocyte sedimentation rate(ESR) and lactate dehydrogenase(LDH) in infants were higher(P < 0.05) and the level of Hb was lower(P < 0.05) than children. The incidence of incomplete KD cases and coronary artery aneurysm in infants increased statistically(P < 0.05). Conclusion: Incomplete KD cases and coronary artery aneurysm are more common in infants younger than 6 months. Examination of coronary artery abnormalities, BCG vaccination erythema, symptoms in digestive system and nervous system and the levels of N%, PLT, ESR, LDH and Hb in time would be helpful for early diagnosis.